United States v. Sanborn was a Supreme Court case decided in 1867. The case involved a dispute between the United States and the Sanborn family over the ownership of a tract of land in California. The Sanborns claimed that they had acquired the land through a Mexican land grant, while the United States argued that the land was part of the public domain and thus belonged to the federal government. The Supreme Court ultimately sided with the United States, ruling that the Sanborns had not acquired valid title to the land. The Court held that the Mexican land grant was invalid because it had not been approved by the United States Congress, as required by the Treaty of Guadalupe Hidalgo. The Court also held that the Sanborns had not acquired valid title to the land through adverse possession, as they had not met the requirements for such a claim. The decision in United States v. Sanborn established the principle that the federal government has the right to reclaim public lands that have been improperly acquired by private individuals.

In United States v. Sanborn, the Supreme Court issued a dissenting opinion in which Justice Field argued that Congress had exceeded its authority under the Constitution by enacting legislation to regulate private contracts between individuals and corporations. He noted that such regulation was not within the scope of congressional power as outlined in Article I, Section 8 of the Constitution, which grants Congress only limited powers over commerce with foreign nations and among states. Furthermore, he argued that this type of regulation should be left up to state legislatures since it involves matters traditionally regulated at a local level. In conclusion, Justice Field asserted that if Congress were allowed to pass laws regulating private contracts then there would be no limit on their power and they could potentially interfere with any aspect of life or business without constitutional justification.